As is well known to those familiar with the production of oil and other hydrocarbons from underground formations, it is often desirable to enhance the flow-rate of hydrocarbons into the well bore after an initial period of production by injecting water into the same reservoir strata to increase its pressure. It is also quite common for the well bore to pass through at least one underground stratum that produces water into the bore that is located at a considerable distance above the hydrocarbon-bearing strata. These water-bearing strata can be isolated by mechanical seals or packers, or by cementing so that water does not find its way into the produced hydrocarbon stream that is typically produced from the bottom of the well bore.
In accordance with current water injection practices, water produced in the well bore or from other well sites is pumped to the surface and fed to the intake of high pressure pumps. Depending on the volume/flow-rate of available water, it may have to be accumulated before delivery to the pumping facility. The discharge from these high pressure pumps is then delivered, often over long distances, e.g., 25 to 30 kilometers, through high-pressure pipes ranging in size from 24 inches to 30 inches in diameter. It will be understood that the capital costs and expenses associated with the construction and operation of this infrastructure for a water injection system that services an oil field stretching over many hundreds or even thousands of square kilometers is substantial. From the above brief description of the prior art methods of providing pressurized water for injection into subterranean formations to enhance hydrocarbon production, the desirability of utilizing an apparatus and method in which this infrastructure is unnecessary is apparent.
It is therefore an objective of this invention to provide a method and apparatus that eliminates the necessity of constructing extensive low and high pressure pipeline systems and pumping stations at the earth's surface in order to deliver pressurized injection water.
It is a further objective of the invention to minimize the distance and, therefore, the associated energy requirements, over which water must be transported from its point of production to the location of its injection into the reservoir formation.
An additional objective of the invention is to provide an apparatus and method for employing an electric submersible pump (“ESP”) injection system that is protected from damage by sand and particulate matter carried by the produced formation water and which minimizes rigging time and costs during installation and retrieval of the completion.
Another objective of the invention is to provide a specifically configured, stand-alone apparatus and a novel method for delivering water from an upper formation zone to a lower formation zone that will permit retrieval and replacement of portions of the completion and will also allow access to the injection zone for logging and well intervention operations without removal of the sand exclusion screens completion.